Treatment of alkaline earth metal petroleum sulfonates



TREATNENT 0F ALKALINE EARTH WTAL PE'IRULEUM SULFGNATES No Drawing. Application July 1, 1954, Faerial No. 440,854

6 Claims. (Cl. 25233) This invention relates to a method for the concentration and improvement of an oil solution of barium petroleum sulfonates by a process of solvent fractionation.

This application is a continuation-in-part of my copending application, Serial No. 297,774, filed July 8, 1952, now abandoned.

During the last decade the petroleum industry has widely adopted the practice of adding detergents to lubricating oils which are used in gasoline and diesel engines. in the operation of these engines, if the fuel is not completely burned or if a film of lubricating oil on the walls of the combustion chamber is partially burned, resinous oxidation products and carbon are formed. These resins produced may build up carbon deposits in the ring belt area and produce ring plugging and ring sticking which result in high oil consumption and may eventually cause wear resulting in inefficient engine operation. The resins may also plug the oil filters. if the oil filter plugs, gritty particles of inorganic matter will not be filtered from the oil, but, instead, will circulate with the oil and lodge between close fitting metallic surfaces and cause abrasion.

The function of the detergent is to peptize the resinous contaminants, to keep them suspended in the oil in a finely divided state, and to prevent their deposition on engine parts.

Among the most widely employed detergents for the above mentioned purpose, are the alkaline earth metal petroleum sulfonates. These substances are usually prepared by the multiple batch acid treatment of lubricating oil stock distillates of low viscosity index or of pressure tars utilizing concentrated or fuming sulfuric acid. The treated stock is allowed to settle forming two phases; a lower layer known as the acid sludge layer, and an upper c-ily layer known as the sour oil layer.

Tarry residues, resinous substances, low molecular weight water soluble sulfonic acids, known as green acids, and disulfonated acids settle out with the acid sludge layer and this sludge layer is usually disposed of as a waste product. The sour oil layer contains oil soluble sulfonates known as mahogany acids, as well as some oil insoluble sulfonates and resinous bodies dispersed in unsulfonated oils of low and high viscosity index. Upon neutralization of the sour oil layer with an excess of an aqueous alkaline earth metal hydroxide or carbonate solution, an oil solution of oil soluble detergents is formed.

At the present time it is common practice to concentrate this oil solution of alkaline earth metal sulfonate detergent to about 50 per cent in a vacuum distillation tower for utilization as a lubricating oil detergent. Concentration is effected by distilling ofi some of the unsulfonated oilpredominantly the high viscosity index hydrocarbon oil components. This concentrated oil solution of detergents, however, is not highly satisfactory as a lubricating oil additive, due to the presence of dispersed resinous substances, tarry matter, and oil insoluble sulfonates which are not removed by distillation. The resinous substances, tarry matter, and oil insoluble rte States atent 2,713,935 Patented July 12, 1955 sults in a product of somewhat low viscosity index.

It should be also mentioned here that some prior art workers have attempted to overcome the disadvantages inherent in the sulfonate detergents resulting from the vacuum distillation of neutralized sour oil by extract ing the sulfonates from the neutralized sour oil with dilute alcohol solutions. Such processes involve neutralization of the sour oil with alkali metal hydroxides, rather than alkaline earth metal hydroxides, so as to facilitate the extraction of the sulfonates from the oil with dilute alcohol solutions. It has been found, however, that although such methods of extraction do efiect a separation of the sulfonates from the oil, the resinous and tarry bodies are also extracted together with sulfonates. It is therefore seen that the vacuum distillation treatment of oil solutions of oil soluble sulfonates or the dilute alcohol extraction treatment of these oil solutions fails to eilect a separation of the sulfonates from the undesirable resins, tarry substances, and lower viscosity index hydrocarbon components.

It is therefore an object of this invention to start with a neutralized sour oil containing baritmi petroleum sulronates, resins, tars, as well as high and low viscosity index hydrocarbon oil components, and to treat this layer in such a manner that there is produced a rafiinate phase composed primarily of barium sulfonatcs, together with the high viscosity index hydrocarbon oil components and an extract phase composed primarily of solvent, resins, and the low viscosity index hydrocarbon oil components.

The process according to the present invention, comprises treating neutralized barium petroleum sulfonate solutions with aqueous methyl ethyl ketone (hereinafter abbreviated MEK) in specific concentrations and amounts so as to accomplish the aforementioned objects. In more detail, a sour oil layer containing mahogany acids, resinous bodies, tarry substances, together with high and low viscosity index hydrocarbon oil components, produced in any manner, is treated with a 10% excess of a saturated aqueous solution of a barium hydroxide or carbonate, in any suitable manner, to produce an oil solution containing barium sulfonates, resinous bodies, tarry substances, together with high and low viscosity index hydrocarbon oil components. This oil solution is contacted with a solvent solution comprising aqueous MEK to thereby produce raflinate and extract phases. The raffinate phase is composed primarily of barium sulfonates, together with the high viscosity index hydrocarbon oil componentsand the extract phase is composed primarily of solvent, resins, and the low viscosity index hydrocarbon oil components. The aqueous MEK solution should contain between about 0.5% and 7.0% water and between about 2 and 3 volumes of this solution are used per volume of charge stock.

The following is given as an example illustrating a method for practicing the present invention when employing barium hydroxide to produce a concentrated barium sulfonate solution of improved purity and which possesses more desirable properties as a detergent additive for lubricating oils.

Example A Mid-Continent crude, namely a Webster crude from Harris County, Texas, was fractionated in a pipestill to obtain a 40/50 distillate and a 60/80 distillate. These distillates had the following properties:

A feed stock was prepared by mixing six parts of 40/50 distillate with four parts of 60/80 distillate, and this feed stock was treated in four separate dumps with by volume of fuming sulfuric acid, so that overall the feed stock was treated with by volume of fuming sulfuric acid. The combined acid sludge layers amounted to about by volume of the feed stock and were discarded. Each acid sludge layer contained tarry residuous, resinous substances, low molecular weight water-soluble sulphonic acids (green acids) and disulfonated acids. The sour oil layer contained oil soluble mahogany acids, oil insoluble sulfonates, and resinous bodies dispersed in unsulfonated hydrocarbon oils of low and high viscosity index. This sour oil layer was neutralized with a 10% excess of a saturated aqueous solution of barium hydroxide. After neutralization the neutralized oil was separated from the aqueous solution by decantation. The thus neutralized oil was filtered to remove inorganic salts and air-blown at approximately 170 F. to remove nearly all traces of Water. The air-blown oil was then separated into two fractions. The approximate molecular Weight of the sulfonates in the air-blown oil was about 1000. The first fraction was subjected to a conventional vacuum distillation treatment to produce a concentrated barium sulfonate oil solution, such as is commonly utilized as a detergent additive for automotive lubricating oils. fraction was treated according to the method of this invention utilizing a two stage batch extraction procedure.

In more detail, one volume of the second fraction entered the first stage at F. and 2.5 volumes of MEK solvent (containing 1 per cent water) was introduced into the second stage. The raifinate layer from the first stage was introduced into the second stage at F., While the extract from the second stage was introduced into the first stage. The final extract phase was withdrawn from the first stage and the final rafiinate phase was withdrawn from the second stage. The table below presents an analysis and comparison of (A) the neutralized, air-blown charge stock, (B) the vacuum distilled residua, and (C) the ratfinate phase of the aqueous MEK extraction.

In Table I, the change in the weight per cent of sulfated ash shows that both the vacuum distillation and MEK extraction concentrated the sulfonates of the charge stock in the residue and rafiinate, respectively. The more important fact which should be noted, however, is that the vacuum distilled residua increased in viscosity while the MEK extraction rafiinate decreased in viscosity. Since the sulfonates have a high viscosity, it would be The second expected that when the sulfonateswere concentrated in the rafiinate by MEK extraction, the viscosity would also increase. The fact that the viscosity of the raifinate actually decreased in comparison with the charge stock indicates that the MEK treatment removed the'high viscosity resincornponents of the charge stock in the extract phase. Also, comparing the viscosity of the charge stock with the vacuum still residuum, it will be seen that the viscosity of the residuum increased more than 500 per cent. Thus, although the vacuum distillation procedure succeeded in accomplishing a concentration of the sulfonates, such procedure also unfortunately concentrated the undesirable high viscosity resin bodies with the desirable sulfonates. Table I, therefore, clearly shows that the a process of this invention is capable of concentrating an the concentrated sulfonate solution is employed as a detergent additive in lubricating oils.

in order to show that the process of this invention also concentrates the high'viscosity index hydrocarbon oil components of the charge stock with the sulfonates in the rafi'inate layer and removes some of the low 'viscosity index hydrocarbon oil components together with resin bodies in the extract solvent, several comparative tests were carried out. These tests comprised preparing a large batch of a typical lubricating oil stock of the type which is commonly employed for automotive engines and which consisted of a mixture of Pennsylvania Neutral lube oil and Pennsylvania Bright Stock. This lar e batch of oil Was then separated into three equal portions and to each of the portions was added a sufiicient amount of one of the sulfonate solutions shown in Table I, so that each portion contained an equal amount of barium sulfonate (indicated by the same weight per cent sulfated ash content). Each of the blends so produced, represented a premium grade detergent oil.

The three detergent oils were as follows:

Oil AA-comprising the aforementioned lube oil base and the sulfonate solution-A of Table 1.

Oil BB--comprising the aforementioned lube oil base and the sulfonate solution B of Table I. 7

Oil CCc0mprising the aforementioned lube oil base and the sulfonate solution C of Table 1.

Inspections of detergent oils AA, BB, and CC are set forth in Table II below:

TABLE II Detergent Detergent Detergent Oil AA Oil BB 0110 O 0. 97 0. 97 0. 97 411.0 454. 398. Q 58. 78 61. 4 58.9 27. 1 25. 5 25. 9 Color ASTM Method 6. 25 7. 6. 5 Viscosity Gravity Constan 0. 824 0.835 0. 833 Viscosity Index 98.0 99. 0 103.0

of this invention, had a greatly improved viscosity index of 103. It is thus apparent that the method-for concentrating suli'onates according to this invention concen- Lates the high viscosity index hydrocarbon oil components of the neutralized sour oil in a raffinate layer containing the sulfonates and concentrates in the extract layer the MEK solvent, together with the undesirable resinous bodies and low viscosity index components of the hydrocarbon oil.

it seems clear that the ability of the instant process to prepare concentrates of barium sulfonates of the character described is due to the utilization of closely con trolled treating conditions. For example, it has been found that it is important to maintain such process variables as the amount and concentration of the aqueous MEK solution within rather close limits in order to attain the novel and highly desirable results of this invention. As stated previously the aqueous MEK solution should contain between about 0.5 and 7.0 per cent water. When the concentration or" water in the aqueous MEK solution exceeds about 7 per cent, the sulfonates will not be concentrated in the raffinate layer but, instead, will be drawn into the extract layer along with the resin bodies and a portion of the low viscosity index components of the oil. On the other hand, when the concentration of water in the aqueous MEK solution decreases below about 0.5 per cent, no clear or definite separation or extraction is eifected since the solvent is no longer selective with the result that the resin bodies, sulfonates and low viscosity index components are about equally divided between the extract and ratfinate phases. The proportion of aqueous MEK solution to charge stock should be between 2 to 3 volumes of MEX solution to one volume of charge stock. if the charge stock has a high viscosity the volume of solvent should be close to 3, while if the stock is of low viscosity, the volume of the solvent should be closer to 2 volumes per volume of charge stock.

it is also necessary that the process of this invention be carried out in a multiple stage extraction unit, since single stage extraction fails to achieve the desired separation and concentration of the sulfonates in the rafiinate phase. A single stage extraction unit lacks the necessary selectivity of separation. A minimum of two stages are needed to permit the solvent to accomplish the desired separation of resins, tars, disulfonates, and low viscosity index hydrocarbon oil components into the extract phase and concentration of the barium sulfonates and high viscosity index hydrocarbon oil components into the raflinate phase. When utilizing two or more stages a solvent additive may be introduced into one of the stages other than the stage into which the solvent itself is being introduced in a manner well-known to those skilled in the art. It has been found preferable in the process of this invention to utilize water as a solvent additive. When employing water as the solvent additive, best results have been obtained by using between 0.5 and 5.0 volumes of solvent additive per volume of charge stock. It will be clear to those skilled in the art that the temperatures in the several extraction stages may vary depending upon the other variables of the process. However, in a two stage extraction unit, it has been found that a temperature of at least 35 F. in the first stage and a temperature below about 85 F. in the second stage produce satisfactory results.

This invention is not to be limited to the specific embodiments shown or the specific examples given, nor to any theories advanced as to the operation of the invention, but in the appended claims it is intended to claim all novelty inherent in the invention.

I claim: I q v 1. A method for producing purified oil solutions of barium sulfonates Which comprises neutralizing with a barium compound a Mid-Continent crude distillate boiling within the lubricating oil range that has been treated with concentrated sulfuric acid and thereafter treating the resulting oil solution of barium sulfonates, resins, and high and low viscosity index hydrocarbon oil components with an aqueous methyl ethyl ketone solution containing between 0.5 and 7.0 per cent water in at least two extraction zones, utilizing between 2 and 3 volumes of aqueous methyl ethyl ketone for each volume of soil solution and separately recovering an extract layer composed primarily of the aqueous methyl ethyl ketone solution, resins, and the low viscosity index hydrocarbon oil components, and a raflinate layer composed primarily of the barium sulfonates and the high viscosity index hydrocarbon oil components.

2. The method according to claim 1 wherein the aqueous methyl ethyl ketone solution contains about 1 per cent water and about 2.5 volumes of this solution is utilized for each volume of the oil solution.

3. The method according to claim 1 wherein between about 0.5 and 5.0 volumes of a solvent additive comprising water per volume of oil solution are introduced into an extraction zone other than the extraction zone into which the ketone solution is being introduced.

4. A method for obtaining concentrated oil solutions of barium sulfonates including the steps of sulfonating a Mid- Continent crude distillate boiling within the lubricating oil range with sulfuric acid under sulfonating conditions to produce an acid sludge layer containing sludge bodies and green sulfonic acids and a sour oil layer containing high and low viscosity index hydrocarbon oil components, mahogany type sulfonic acids, and undesirable components, separating said sour oil layer and neutralizing with a barium compound to convert the mahogany type sulfonic acids to barium sulfonates, contacting the thus neutralized mixture with an aqueous methyl'ethyl ketone solution containing between about 0.5 and 7.0 per cent Water in at least two extraction zones utilizing between 2 and 3 volumes of aqueous methyl ethyl ketone solution for each volume of said mixture, and separately recover ing an extract layer, composed primarily of the aqueous methyl ethyl ketone solution, undesirable components and the low viscosity index hydrocarbon oil components and a raffinate layer composed primarily of the barium sulfonates and the high viscosity index hydrocarbon oil components.

5. The method according to claim 4 wherein the aqueous methyl ethyl ketone solution contains about 1 per cent water and about 2.5 volumes of this solution is utilized for each volume of the oil solution.

6. The method according to claim 4 wherein between about 0.5 and 5.0 volumes of a solvent additive comprising water per volume of oil solution are introduced into an extraction zone other than the extraction zone into which the ketone solution is being introduced.

References Cited in the file of this patent UNITED STATES PATENTS 2,236,933 Beck Apr. 1, 1941 2,514,733 Vold et a1 July 11, 1950 

1. A METHOD FOR PRODUCING PURIFIED OIL SOLUTIONS OF BARIUM SULFONATES WHICH COMPRISES NEUTRALIZING WITH A BARIUM COMPOUND A MID-CONTINENT CRUDE DISTILLATE BOILING WITHIN THE LUBRICATING OIL RANGE THAT HAS BEEN TREATED WITH CONCENTRATED SULFURIC ACID AND THEREAFTER TREATING THE RESULTING OIL OF BARIUM SULFONATES, RESINS, AND HIGH AND LOW VISCOSITY INDEX HYDROCARBON OIL COMPONENTS WITH AN AQUEOUS METHYL ETHYL KETONE SOLUTION CONTAINING BETWEEN 0.5 AND 7.0 PER CENT WATER IN AT LEAST TWO EXTRACTION ZONES, UTILIZING BETWEEN 2 AND 3 VOLUMES OF AQUEOUS METHYL ETHYL KETONE FOR EACH VOLUME OF SOIL SOLUTION AND SEPARATELY RECOVERING AN EXTRACT LAYER COMPOSED PRIMARILY OF THE AQUEOUS METHYL ETHYL KETONE SOLUTION, RESINS, AND THE LOW VISCOSITY INDEX HYDROCARBON OIL COMPONENTS, AND A RAFFINATE LAYER COMPOSED PRIMARILY OF THE BARIUM SULFONATES AND THE HIGH VISCOSITY INDEX HYDROCARBON OIL COMPONENTS. 